1. Field of the Invention
The present invention relates to a heat and mass transfer mechanism, more specifically to compact integrated blood pump oxygenators.
2. Background Information
U.S. patent application Publication No. 2008-0199357, which is incorporated herein by reference, also relates to an integrated centrifugal blood pump-oxygenator having a rotational body being rotatably arranged in a rotor-housing of the bottom. According to the invention disclosed in U.S. patent application Publication No. 2008-0199357, the rotational body is magnetically journalled in a contact free manner with respect to the rotor-housing. U.S. Patent Application Publication Number 2008-0199357 provides an generally accurate backdrop for describing the field of integrated centrifugal blood pump-oxygenators.
As reported in U.S. patent application Publication No. 2008-0199357 lung diseases are the third largest cause of death in the United States of America, accounting for approximately 1 out of every 7 adult deaths. It has been estimated that 30 million Americans are living with chronic lung disease. Adult respiratory distress syndrome (ARDS) has been reported to afflict approximately 150,000 patients annually in the U.S, and despite advances in critical care, mortality remains around 40-50%. Currently available therapies for patients with chronic respiratory failure include, for example, ventilation and extracorporeal membrane oxygenation (ECMO). In intensive care medicine, extracorporeal membrane oxygenation (ECMO) is an extracorporeal technique of providing both cardiac and respiratory support oxygen to patients whose heart and lungs are so severely diseased or damaged that they can no longer serve their function.
ECMO systems are attractive since they closely simulate physiological gas exchange. Attempts have been made to integrate multiple components of cardiopulmonary, ECMO-systems into single structures so as to eliminate or minimize the need for the extension of lengthy, blood-filled tubes. Various integrated pump-oxygenators have been described as discussed in U.S. Pat. Nos. 5,217,689; 5,266,265; 5,270,005; 5,770,149; 4,975,247; 5,429,486; 6,963,222; and 6,730,267, which are incorporated herein by reference.
U.S. patent application Publication No. 2008-0199357 suggests there are drawbacks associated with many of these integrated pump-oxygenators, including non-uniform blood flow through the fiber membranes and the existence of laminar boundary flow zones between blood cells and fiber membranes. Non-uniform blood flow across the fiber membranes results in hyper- and hypo-perfusion of the blood in flow paths. U.S. patent application Publication No. 2008-0199357 discusses efforts to decrease the effect of the boundary layer include increasing shear rate and/or turbulence of the blood flow path by the introduction of secondary flows, for example, by directing blood to flow at a substantial angle, such as perpendicular, to the fiber membranes. U.S. Pat. No. 4,639,353, which is incorporated herein by reference, discloses the use of an arrangement of bundles of hollow fibers perpendicular to the direction of blood flow via a series of flow guide structures. U.S. Pat. No. 5,263,924, which is incorporated herein by reference, discloses the use of an integrated centrifugal pump and membrane oxygenator comprising hollow fibers, which are displaced circumferentially in a ring around an impeller of the centrifugal pump and through which blood is pumped for oxygenation. See also U.S. Pat. No. 3,998,593 issued to and U.S. Pat. No. 4,490,331 which are incorporated herein by reference.
Other efforts to decrease the effect of the boundary layer include actively rotating hollow fiber membranes or moving fiber membranes in the path of blood flow, examples of which are described in U.S. Pat. Nos. 5,830,370; 6,217,826; 6,503,450; 6,723,284; and 7,122,155, which are incorporated herein by reference.
Additional patents and publications giving a general overview of conventional blood pump-oxygenators include U.S. Pat. No. 6,929,777, 7,927,544, U.S. Publication Nos. 2002-0057989, 2004-0219059, 2007-0249888, 2008-0190870, 2009-0175762, 2010-0101657, and 2010-0288703 which are incorporated herein by reference.
Despite improvements in the performance and design of conventional blood pump-oxygenators, there remains a need for a more compact and efficient blood-pump oxygenator with less pronounced or fewer drawbacks. Thus, there is a need for a compact, efficient and minimally-traumatic pump-oxygenator. It is an object of the present invention to provide such an improved blood pump-oxygenator. This and other objects and advantages, as well as additional inventive features, will become apparent the detailed description provided herein.